Toothbrush attachment for an electric toothbrush



Sept. 10, 1968 M. A. MORET 3,400,417

TOOTHBRUSH ATTACHMENT FOR AN ELECTRIC TOOTHBRUSH Filed Nov. 1, 1966 FIG. 2 FIG. 3

INVENTOR Michel A. Moref Q; wEZJFZVfl ATTORNEYS United States Patent 3,400,417 TOOTHBRUSH ATTACHMENT FOR AN ELECTRIC TOOTHBRUSH Michel A. Moret, Chene-Bourg, Geneva, Switzerland, as-

signor to Etablissement AESUP, Vaduz, Liechtenstein,

a firm of Liechtenstein Filed Nov. 1, 1966, Ser. No. 591,309 12 Claims. (Cl. -22) This invention relates to a toothbrush attachment for an electric toothbrush, and particularly such an attachrrtilergt for a motor unit having a rotationally oscillatory s a t.

In US. Patent No. 2,917,758, an electrically-operated toothbrush is described comprising a motor unit having a shaft on the end of which a brush head is mounted. The shaft is rotationally oscillated in use, and the corresponding movement of the brush bristles effects a brushing of the teeth in the longitudinal direction thereof.

In order to permit the electrically-operated toothbrush to be used by different members of the family, and to permit replacement of worn brush heads, it is desirable to arrange the brush portion for convenient attachment to the motor unit and removal therefrom. Further, for hygienic reasons it is desirable for the brush attachment to include all portions normally inserted in the mouth. This may be accomplished by providing an attachment having a stem of sufficient length, with the bristles at one end and a coupling at the other end adapted for attachment to the shaft of the motor unit.

For greatest usefulness, the coupling should fulfill several requirements. It should permit convenient attachment and removal, and be adapted to rotationally oscillate the brush stem in a positive manner without undue wear. It should also resist forces tending to detach the brush from the motor unit when the bristles are pressed against the teeth during cleaning. Finally, it is advantageously designed so that it can be formed by molding in plastic material, so that the attachment unit can be economically manufactured without metal portions which would contact the teeth during the cleaning operation and gave rise to discomfort or injury.

In US. Patent No. 3,088,148 a toothbrush attachment is described which meets the foregoing requirements. The coupling has a socket of non-circular cross-section, preferably rectangular, which mates with the shaft end of the motor unit. An open slot in the wall of the socket has opposed recesses which engage a transversely-extending pin on the motor shaft end to yieldably secure the attachment thereto. A blind counterslot on the opposite wall of the socket provides flexibility which facilitates attachment and removal.

This attachment has provide to be quite satisfactory. However, one disadvantage has been found in practice. It is possible for a user, either inadvertently or through failure to read directions, to place the attachment on the shaft end 180 from the proper orientation. Thus the pin does not engage the recesses in the open slot and the attachment is likely to fall off in use. Further, repeated wrong attachments eventually wear the pin on the shaft so that it no longer functions properly, or it may be broken off.

The present invention provides a coupling which prevents wrong attachment while retaining the advantages of the prior attachment, and has further advantages.

In accordance with the invention, a coupling is provided having a socket of non-circular cross-section with a recessed slot therein, and a transversely projecting fin is provided on the wall of the socket in predetermined position with respect to the slot. The stem is enlarged at the base of the coupling to extend laterally beyond the wall of the 3,400,417 Patented Sept. 10, 1968 ICC socket. Preferably the fin is on the opposite side of the socket from the slot. Also, preferably, the enlarged stem at the base of the coupling forms a shoulder which extends laterally at least to the outer edge of the fin, and the fin is united therewith. The fin serves as an orientation element during attachment, and also provides added strength to the coupling.

The motor unit has a shaft end similar to that described above, and the casing is formed so as to extend to approximately the tip of the shaft end and encircle the end in spaced relationship to provide an opening for insertion of the coupling end of the toothbrush attachment. The opening has an enlarged sector at a predetermined angular position away from the rest angular position of the pin on the shaft end. This enlarged sector accommodates the fin on the toothbrush attachment, and its angular extent and relationship to the shaft pin are predetermined to prevent improper reversal of the attachment. 'With an attachment in which the fin extends to the shoulder of the enlarged stem, as is preferred, the enlarged sector extends over an angle at least as great as the amplitude of rotational oscillation of the shaft end so as not to interfere with proper operation.

The invention will be described more fully in connection with a specific embodiment thereof wherein additional features will in part be pointed out and in part be obvious to those skilled in the art.

In the drawings:

FIG. 1 is an overall view of the motor unit with the toothbrush attachment is place;

FIG. 2 is an enlargement of a portion of FIG. 1, with the attachment removed from the motor unit shaft and internal details shown;

FIG. 3 is a view at right angles to FIG. 2;

FIG. 4 is an end view of the toothbrush attachment, taken from the coupling end; and

FIG. 5 is an end view of the motor unit with the toothbrush attachment removed.

Referring to the drawings, a motor unit 10 is shown in the form of a handle with internal motor means (not shown) for producing rotational oscillation of a shaft mounted in the casing having a shaft end 11. The shaft end has a non-circular cross-section, preferably generally rectangular as shown. Slight rounding of edges may be present, and the narrow sides 13 may have a slight curvature. A transversely extending pin 14 is provided. Advantageously this is located on one of the wide sides of the shaft end and spaced a substantial distance from the tip, as illustrated. The casing 10 extends to approximately the tip of the shaft end 11 and encircles the end in spaced relationship to provide an opening 15 for insertion of the toothbrush stem. The opening has an enlarged sector 16 at a predetermined angular position away from the rest angular position of pin 14, and is here shown as on the opposite side of the shaft from the pin. I

The toothbrush attachment comprises a stem 17 having laterally extending bristles 18 at one end thereof. A coupling 19 is provided at the other end of the stem and has a longitudinally extending socket 21 of non-circular crosssection adapted to mate with the shaft end 11. As specifically shown, the socket is generally rectangular with a slight curvature of the narrow sides 22, as best seen in FIG. 4. A longitudinally extending slot 23 is provided in the wall of the socket and is open toward the lower end of the stem, as viewed in FIG. 2. Opposed transversely extending recesses 24 are formed in the sides of the slot near its open end and are adapted to engage pin 14 when in mated position, thereby releasably securing the attachment on the shaft. The width of the slot is less than the width of the socket in the corresponding direction. If de- 3 sired, a blind couner slot 25 may be provided opposite the open slot 23.

A transversely projecting fin 26 is provided on the wall of the socket in predetermined position with respect to the slot, the position being selected so that the fin may pass through the enlarged sector 16 of the motor unit when the attachment is properly oriented, but not when it is improperly oriented. As will be apparent from the relative dimensions of the sector 16 and the fin 26, the fin does not precisely guide the attachment into mating position. Rather, the non-circular cross-section of the coupling serves to guide the mating, but the fin prevents inserting the attachment opposite to its proper orientation. Thus, the user can only insert the attachment in the proper orientation for pin 14 to engage the recesses 24 in the open slot.

The stem is enlarged at the base of the coupling, as shown at 27, so as to extend laterally beyond the wall of the socket. Preferably, as shown, the enlarged stem forms a shoulder 28 which extends laterally to at least the outer edge 29 of the fin, and the fin is united therewith. Thus the fin strengthens the wall of the socket, particularly when counter slot 25 is provided, and also adds rigidity to the coupling end.

It is desirable to have the bristles 18 and open slot 23 on the same side of the brush stem, with the fin on the opposite side. During use, pressure of the bristles 18 against the teeth produces a force on the coupling which tends to move the tips of bristles 18 closer to the axis of shaft 11. If carried to an extreme, such that the tips of the bristles were on the axis, the tips would not move and hence would not produce the desired cleaning action. With the orientation of the slot 23 and fin 26 as shown, these forces are resisted and there is a proper effective cleaning action.

With the fin 26 united with the enlarged section 27 of the toothbrush stem, the enlarged sector 16 must extend over an angle at least as great as the amplitude of rotational oscillation of the shaft end, so as not to obstruct the movement of the fin or break it off. Advantageously, the sector 16 extends over a somewhat greater angle, so as to avoid close tolerances in manufacture. However, the angular extent of the sector should not be so great as to allow reversal of the brush stem 17 by 180 duringattachment. Thus the enlarged sector is positioned away from the rest angular position of pin 14 and preferably on the opposite side of the shaft from the pin, as best seen in F IG. 5.

The toothbrush attachment shown is adapted for molding in a plastic material, such as nylon, with the bristles set in known manner. The enlarged end 27 and the fin 26 are particularly advantageous in such case to provide adequate strength, especially since the coupling 19 is of relatively small diameter to avoid undue bulk.

I claim:

1. A toothbrush attachment which comprises a stem having lateraly extending bristles at one end thereof, a coupling at the other end of said stem having a longitudinally extending socket of non-circular cross-section, a longitudinally extending slot in the wall of said socket and open toward said other end of the stem, the width of the slot being less than the width of the socket in the corresponding direction, opposed transversely extending recesses in the sides of said slot near the open end thereof, and a transversely projecting fin on the wall of said socket in predetermined angular position with respect to said slot, said stem being enlarged at the base of said coupling to extend laterally beyond the wall of said socket.

2. A toothbrust attachment in accordance with claim 1 in which said fin is on the opposite side of the socket from said slot.

3. A toothbrush attachment in accordance with claim 2 in which said enlarged stem at the base of the coupling forms a shoulder which extends laterally at least to the outer edge of said fin and the fin is united therewith.

4. A toothbrush attachment in accordance with claim 3 in which said socket is of generally rectangular crosssection with the longer dimension thereof extending generally perpendicularly to said bristles and said slot is on the same side of the stem as said bristles.

5. A toothbrust attachment for a motor unit having a rotationally oscillatory shaft end of non-circular crosssection with a transversely extending pin spaced a substantial distance from the tip thereof and a casing extending to approximately the tip of said shaft end and encricling the end in spaced relationship to provide an opening for insertion of a toothbrush attachment, said opening having an enlarged sector at a predetermined angular position away from the rest angular position of said pin, said toothbrush attachment comprising a stem having laterally extending bristles at one end thereof, a coupling at the other end of said stem having a longitudinally extending socket of non-circular cross-section adapted to mate with said shaft end, a longitudinally extending slot in the wall of said socket and open toward said other end of the stem, opposed transversely extending recesses in the sides of said slot near the open end thereof adapted to engage said pin when in mated position, and a transversely projecting fin on the wall of said socket at an angular position with respect to said slot predetermined to be within said enlarged secor during insertion of the toothbrush stem, said stem being enlarged at the base of said coupling to extend laterally beyond the wall of said socket.

6. A toothbrush attachment in accordance with claim 5 for a motor unit in which said enlarged sector is on the opposite side of the shaft from said pin, said attachment having said fin on the opposite side of the socket from said slot 7. A toothbrush attachment in accordance with claim 6 in which said enlarged stem at the base of the coupling forms a shoulder which extends laterally at least to the outer edge of said fin and the fin is united therewith.

8. A toothbrush attachment in accordance with claim 7 in which said socket is of generally rectangular crosssection with the longer dimension thereof extending generally perpendicularly to said bristles and said slot is on the same side of the stern as said bristles.

9. An electric toothbrush which comprises a casing forming a handle, a shaft mounted in said casing and motor means for producing rotational oscillation thereof, said shaft having a shaft end of non-circular cross-section and a transversely extending pin spaced a substantial distance from the tip thereof, said casing extending to approximately the tip of said shaft end and encircling the end in spaced relationship to provide an opening for insertion of a toothbrush stem, said opening having an enlarged sector at a predetermined angular position away from the rest angular position of said pin, a removable toothbrush stem having laterally extending bristles at one end thereof, a coupling at the other end of said stem having a longitudinally extending socket of non-circular cross-section adapted to mate with said shaft end, a longitudinally extending slot in the wall of said socket and open toward said other end of the stem, opposed transversely extending recesses in the sides of said slot near the open end thereof adapted to engage said pin when in mated position, and a transversely projecting fin on the wall of said socket at an angular position with respect to said slot predetermined to be within said enlarged sector during insertion of the toothbrush stem, said stem being enlarged at the base of said coupling to extend laterally beyond the wall of said socket.

10. An electric toothbrush in accordance with claim 9 in which said enlarged sector extends over an angle at least as great as the amplitude of rotational oscillation of said shaft end, and said enlarged stem at the base of the coupling forms a shoulder which extends laterally at least to the outer edge of said fin and the fin is united therewith.

11. An electric toothbrush in accordance with claim 10 in which said enlarged sector is on the opposite side of the shaft from said fin, and said fin is on the opposite side of the socket from said slot.

12. An electric toothbrush in accordance with claim 11 in which said shaft end and socket are of generally rectangular cross-section, said pin and slot are on one of the broad sides of the shaft end and socket respectively,

and said bristles are on the same side of said stem as said slot.

References Cited UNITED STATES PATENTS 3,088,148 5/1963 Moret EDWARD L. ROBERTS, Primary Examiner. 

1. A TOOTHBRUSH ATTACHMENT WHICH COMPRISES A STEM HAVING LATERALLY EXTENDING BRISTLES AT ONE END THEREOF, A COUPLING AT THE OTHER END OF SAID STEM HAVING A LONGITUDINALLY EXTENDING SOCKET OF NON-CIRCULAR CROSS-SECTION, A LONGITUDINALLY EXTENDING SLOT IN THE WALL OF SAID SOCKET AND OPEN TOWARD SAID OTHER END OF THE STEM, THE WIDTH OF THE SLOT BEING LESS THAN THE WIDTH OF THE SOCKET IN THE CORRESPONDING DIRECTION, OPPOSED TRANSVERSELY EXTENDING RECESSES IN THE SIDES OF SAID SLOT NEAR THE OPEN END THEREOF, AND A TRANSVERSELY PROJECTING FIN ON THE WALL OF SAID SOCKET IN PREDETERMINED ANGULAR POSITION WITH RESPECT TO SAID SLOT, SAID STEM BEING ENLARGED AT THE BASE OF SAID COUPLING TO EXTEND LATERALLY BEYOND THE WALL OF SAID SOCKET. 